Slate or blackboard eraser



, tine or isinglass, such solution,

UNITED STATES PATENT OFFICE.

DOMINICK E. DEMPSEY, OF GENEVA, NEW YORK.

SLATE OR BLA CKBOARD ERASER.

SPECIFICATION forming part of Letters Patent No. 517,034, dated March 27, 1894. Application filed July 8,1893. Serial No. 479,461- (No specimens.)

To all whom it may concern.-

Be it known that I, DoMINIoK E. DEMPSEY,

a citizen of the United States, residing at Ge-,

neva, in the county of Ontario and State of New York, have invented certain new and useful Improvementsin Slate and Blackboard Erasers; and I do hereby declare the following to be afull, clear, and exact description of theinvention, such as will enable others skilled in the art to which it appertains to make and use the same.

The object of my invention is an improved slate and blackboard eraser to produce a superior erasive material for the purpose of erasing chalk, slate or crayon marks from slates and blackboards. For this purpose, I add to ordinary paper pulp, preferably that known as blotting paper pulp, a solution composed of one part of saccharin, three parts of potassium bichromate and six parts of gelaaside from the water, bearing the relation of about one part of chemicals to ninety nine parts of dry paper material. While the proportions of the chemicals as stated are preferably used, they may be varied both with relation to each other and to the pulp. The pulp having been thus treated, is under heat and pressure, made into dry sheets, the dimensions and thickness of which may be varied at will. These dry sheets are then divided into small masses, blocks or tablets, suitable to be held conveniently in the hand and used for the purposes mentioned. The material obtained by this process iseconomical in cost, light in weight, readily made into convenient shapes and sizes, compact and durable, and remarkably effective for completely erasing, with slight friction, chalk, slate and crayon marks from slates and blackboards, without doing any injury to the surfaces thereof. In using this material for such erasing purposes, it is unnecessary to use water or other moisture. In these respects this material is superior to any other material heretofore used for the purposes described.

Having thus described my invention, what I claim, and desire to secure by Letters Patent, is-

A block, tablet or mass of erasive material for the purpose set forth, composed of paper, gelatine, saccharin, and potassium bichromate, substantially as described.

In testimony whereof I have signed my name to this specification in the presence of two subscribing witnesses.

DOMINIOK E. DEMPSEY.

Witnesses:

ALBERT B. GUILBERT, J. H. PICKETT. 

